Nov. 24, 2010 -- Legal highs soon will be illegal across the U.S., the Drug Enforcement Administration (DEA) said today.

The DEA is using its emergency powers to make K2, Spice, and other "legal high" herbal products Schedule I controlled substances -- that is, illegal drugs with no permitted medical use. The declaration will take effect after a mandatory 30-day waiting period, and will have the effect of law for at least a year.

Some 15 states already have banned some or all "legal high" products. When the waiting period expires, sale or possession of the substances will be a federal crime.

"When the final rule is published, it gives us the authority to do the same investigations as for any other controlled substance," DEA spokeswoman Barbara Carreno tells WebMD.

Specifically, the soon-to-be banned drugs are five designer drugs that mimic the effects of THC, the active ingredient in marijuana. The drugs are JWH-018, JWH-073, JWHY-200, CP-47,497, and cannabicyclohexanol.

"Legal high" products claim to be mixtures of herbs that can be smoked for a psychedelic effect. But the herbs listed on the package label often are missing from the actual product. Instead, the product contains a leafy mixture that is spiked with a designer drug -- usually one of the five drugs listed by the DEA.

The same product often is spiked with different doses of different drugs, making it impossible for users to know what they are taking.

Like THC, the active ingredient in marijuana and other forms of cannabis, these synthetic cannabinoids turn on the cannabinoid receptors (switches that trigger activity) found on many cells in the body. The brain is particularly rich in the CB1 cannabinoid receptor.

But most synthetic cannabinoids are quite different chemical structures from THC. And unlike cannabis, which has been used by humans for millennia, the new drugs have never been tested in humans.

JWH-018 was first made for experimental purposes in 1995 in the lab of Clemson University researcher John W. Huffman, PhD.

"Nobody knows anything about how these new compounds act in the human body. Anecdotal reports say they stick around in the body for quite a long time," Huffman told WebMD earlier this year.

The DEA says the American Association of Poison Control Centers has received more than 1,500 calls relating to products spiked with these designer cannabinoids. The calls came from 48 states and the District of Columbia.

The drugs appear to come from foreign sources. The DEA says that U.S. Customs in 2010 has intercepted multiple shipments of two of the drugs, including one shipment of over 50 kilograms.